Directional drilling equipment

ABSTRACT

Directional drilling equipment is disclosed that employs a downhole motor to rotate the bit, while the drill string provides the weight on the bit. The equipment has a sleeve between the bit and the motor that has a bend or inflection point such that the bit makes the desired angle with the axis of the drill string. Torque from the motor is transmitted through the inflection point to the bit by a shaft and a dual universal joint housed in the sleeve. None of the weight on the bit or the end thrust of the motor is transmitted to the shaft.

United States Patent Inventors Appl. No.

Filed Patented Assignee DIRECTIONAL DRILLING EQUIPMENT 11 Claims, 10Drawing Figs.

US. Cl 175/74, 175/256 Int. (I E211) 7/08 FleldotSeareh 175/73,74,92,101, 256, 320

mm lglflll [56] References Cited UNlTED STATES PATENTS 1,850,403 3/1932Lee 175/74 3,190,374 6/1965 Caperan et a1 175/256 X FOREIGN PATENTS1,247,454 10/1960 France 175/73 Primary Examiner-David H. BrownAttorney-Hyer, Eickenroht & Thompson ABSTRACT: Directional drillingequipment is disclosed that employs a downhole motor to rotate the bit,while the drill string provides the weight on the bit. The equipment hasa sleeve between the bit and the motor that has a bend or inflectionpoint such that the bit makes the desired angle with the axis of thedrill string. Torque from the motor is transmitted through theinflection point to the bit by a shaft and a dual universal joint housedin the sleeve. None of the weight on the bit or the end thrust of themotor is transmitted to the shaft.

PATENTEDJUNZZISYI 3.586116 sum 2 or 4 W/ad/m/r 77/aJpoZr/4y ATTOR/VFYJPATENTEU JUN22 1971 SHEET 3 OF 4 DIRECTIONAL DRILLING EQUIPMENT Thepresent invention relates generally to the art of drilling wells such asoil wells in directional or deviated fashion by means of undergroundrotating drilling motors.

For acquiring mastery in this art, it is important to be able to givethe drilling tool (drilling bit, core drill or the like) an inclinationwhich must not exceed a few sexagesimal degrees with respect to the axisof the drill string. The easiest solution consists in interposing acranked union or joint between the tool-driving motor and the drillstring. However, such a method only gives limited possibilities and itoften happens than an inclination of the order of 30 may not be exceededin this way because the weight of the motor then operates reversely ofthe sought effect. Moreover, the provision of a cranked union limits thepermissible length and consequently the power of the motor.

In view of this, attempts were made to arrange the cranked joint underthe motor between the latter and the tool.

Several types of joints or subs of this type have already been developedand tested. However, their duration is very limited and none of themseems to have reached the manufacturing stage. The chief defects of suchconstructions were that the principles of homokinetics were notrespected and that a pushing stress was transmitted simultaneously withthe torque. This seems to be detrimental to their behavior in service.

An object of the invention is to remedy the disadvantages of knownconstructions in this technical field and to provide an equipment fordirected drilling wherein the driving force is fumished by anunderground rotating motor capable of dissociating axial thrust stressesfrom torque-transmitting stresses while permitting the use of ahomokinetically acting driving device owing to such a novel constructionthat such device does not transmit axial stresses of any importance.

Another object of the invention is to provide a new or improvedequipment for directed drilling comprising in known fashion aninflection point or cranked portion, an underground rotary motor, amotor driven drilling tool, axial thrust bearings and characterized bythe fact that the thrust bearing that takes the reaction of the tool andthe bearing that supports the axial push of the motor or that part ofthe motor situated above the inflection point are dissociated orsegregated and arranged on the opposite sides of said inflection point,at least one part of the motor being located above the inflection point,a distortable driving device (advantageously of homokinetic nature)being provided opposite the inflection point of the drilling stringbetween the shafts extending through the straight upper and lower partsof the equipment.

Owing to the segregation over and under the inflection point between thebearings and the absorbing means for the axial stresses due to the toolreaction and the pushing stresses due to the motor elements, there isthus created opposite said inflection point in the drive shafting aso-called quiet zone which does not transmit axial stresses, therebypermitting to provide at said point a driving device which substantiallytransmits angular stresses exclusively.

A further object of the invention is to provide an equipment asaforesaid comprising a particularly advantageous construction includinga driving device made up of a dual universal joint performing ahomokinetic driving action while eliminating axial stresses at thispoint, thereby making it possible to employ universal joints ofconventional structure, for example of the type as commonly used onautomotive vehicles.

Yet a further object of the invention is to provide an axially slidableangular driving device interposed in the line of shafting on either theone or the other side of the aforesaid distortable driving device,advantageously on the tool side so as practically to eliminate axialthrust transmission or axial vibrations from said distortable device,elastic means being advantageously provided for attenuating or absorbingangular impacts and vibrations.

A still further object of the invention is to provide an equipment asaforesaid comprising means for advantageously and continuously adjustingthe angle defined at the inflection point between 0 and a maximum valuewithout any need to dismantle entirely the equipment.

The underground motor may be arranged entirely over the inflection pointor partly over and partly under said point.

With these and such other objects in view as will incidentally appearhereafter, the invention comprises the novel construction andcombination of parts that will be now described hereafter with referenceto the accompanying diagrammatic drawings exemplifying the same andforming a part of the present disclosure.

In the drawings:

FIG. I is a diagrammatic view of this improved grounddrilling equipmentincluding an underground rotating motor connected with the tool by acranked joint.

FIG. 2 is a view showing the relative positions of the three axes of themotor, deviating sleeve and tool.

FIG. 3 is a graph illustrating the variation law of the several anglesdefined by the three aforesaid axes.

FIG. 4 is a detailed view of that portion of the equipment capable ofdefining the varying angle of the cranked portion in the positionoccupied thereby for performing a straight drilling operation.

FIG. 5 is a partial view corresponding with FIG. 4 but with a positionof maximum deviation.

FIG. 6 is a view showing a constructional form of the axially slidableangular coupling, half this figure being in axial section.

FIG. 7 is an under plan view corresponding with FIG. 6, half this figurebeing in transverse section.

FIG. 8 is a sectional view on the line VIII-VIII in FIG. 6.

FIG. 9 is a view representing a constructional modification of what isshown in FIG. 8.

FIG. 10 shows an embodiment of the equipment having a stationary crankedportion.

In the showing of FIG. I, the tool I which comprises a drilling bit isdriven by a shaft 2 fitted in a body member 3 and abutted against it bymeans of an axial bearing 4 which takes and absorbs the tool reaction.The shaft 2 is angularly connected with a shaft 6 through an axiallyslidable angular coupling 5. The shaft 6 is driven by a device made upof a pair of universal joints 7, 7 interconnected by a shaft 8. Thisdevice is engaged by a shaft 9 accommodated in a body member 10containing the underground rotary motor which may be of any conventionaltype. The axial bearing for this motor is shown at 11.

It will be seen from the drawings that the shafts 6 and 9 are mounted inradial bearings 12, 13 and that the axes of the body members 3, l0define an angle so as to permit deviated drilling to take place. 14designates in diagrammatic fashion a cranked union. It will be seen thatsaid union is arranged substantially midway of the ends of the shaft 8.This union 14 may be stationary or may have a variable and adjustableangle as described more in detail hereafter.

It will be understood that, during the operation, the reaction of thetool I and the axial thrust stress exerted by the motor are respectivelytaken and absorbed by the thrust bearings 4, 11 whereby a zone relievedfrom axial stresses is provided opposite the union or cranked portion14. In this zone merely prevails a transmission of angular forces fordriving the tool from the motor. This permits a dual universal jointdevice of the illustrated type to be used for performing the drivingaction thereby ensuring a homokinetic transmission that cannot absorbaxial stresses.

In the showing of FIG. 2 is illustrated at x-x' the axis of the drillingstring or motor, at y-y' the axis of the tool and tool holder and at zz'the axis of a deviating sub of the type described hereafter and shown inFIG. 1 as the union or joint 14.

A particularly advantageous feature resides, as described hereafter, inthe possibility of varying the deflection angle 0 (defined between theaxes x-x and y-y) between zero and a maximum value:

0,,,,, ,=2a by turning y-y' around z-z'.

In the graph constituting FIG. 3 is illustrated the variation of theangle in terms of the angle a delineated between the plane defined bythe axes of x-x and z-z' and the plane defined by the axes y-y' and z-z'in the case of a union whose (1 angle is equal to 1.5.

In said graph are also represented the linear variations of the B angledefined between the plane xx'zz' and the plane xxyy the knowledge ofwhich is useful for relative reference of the several elements of anadjustable union.

In the constructional form shown in FIGS. 4 and 5, a turbodrill is usedthe body member of which is indicated by 15 while its shaft 16terminates adjacent the tool in a lower shaft 17 arranged inside astator union 18. This shaft 17 can resolve in a radial bearing 19 and isrigidly connected with a universal joint 20 housed in a sleeve 21. Theuniversal joint 20 is connected via a shaft 22 with another universaljoint 23 which drives a further shaft 24 revoluble in radial bearings 25and connected through an axially slidable angular coupling 26 with theshaft 27 that imparts rotation to the tool.

It will be easily seen that the motion derived from the shaft 27 ishomokinetic with respect to that of the shaft 16 no matter what theirrelative angular positions may be. The shaft 27 is radially guided byits own set of bearings and bushes 28 and its axial displacements arelimited by a double-acting abutment 29 which absorbs the tool reactionAlthough this is not shown but as herebefore stated, the axial thrustexerted by the motor is absorbed by an independent thrust bearing.

The universal joint system is housed in the sleeve 21 and in a sleeve 30connected via a bearing 31 and a union 32 with the body or housing 33containing the axial bearing 29.

The sleeves 21, 30 are interconnected by a sleeve 34 having a shoulder35 and a male-threaded portion 36 which can be screwed into afemale-threaded portion of the sleeve 30. As is visible in FIG. 4, theaxis of the female-threaded portion defines an 0: angle with the axis ofthe sleeve 30. This is also true for the axis of the sleeve 34.Moreover, the axis of the sleeve 21 slants by an angle equal to a whichis preferably equal to the at angle with respect to the axis of theabutted faces of its lower end on the shoulder 35.

It will thus be seen that if the sleeve 30 is revolved about the sleeve34, the angle 6 defined between the axes of the sleeves 21, 30 may bevaried by 0-0: up to the value art-a which, where a=a, gives thefollowing limit values:

Practically speaking, the maximum value used for 0 does not exceed 3 sothat al305 In the graph constituting FIG. 3, the variation of 0 in termsof the angular motion of the sleeve 21 relatively to the sleeve 34 isclearly shown.

The showing of FIG. 4 corresponds with the aligned position, i.e., with6=0.

In operation, the sleeve 21 should be axially and angularly rigid withthe sleeve 30. In order to achieve this rigid interconnection, there isprovided (as shown in FIG. 4) a spacing ring 37 interposed between theabutted faces of the sleeves 21, 30. Such ring is keyed or otherwisemade angularly fast at 38 with the sleeve 34. Furthermore, the sleeve 21is keyed in adjustable fashion by means of pegs 39 engaged intosequentially arranged holes 40 formed in the end face of the sleeve 21.

However, this angular interconnection might be also ob tained byproviding the abutment face between the shoulder 35 and the base of thesleeve 21 with crowns of teeth or mutually interlocked ribs and flutes.

When it is desired to vary the relative inclination angle 0, it is onlysufficient to unlatch the threaded portion 36 then to rotate the ring 37with respect to the sleeve 21 by the required angle a and to reestablishthe keying effect and to relatch the threaded portion. Advantageously,the connecting elements may be provided with reference marks and/orscale lines permitting the necessary a angle to be determined so as toobtain an angle 0 having the desired value.

In FIG. the above-described device is represented in its position ofmaximum deviation.

In the showing of FIGS. 6 to 8 is illustrated a possible constructionalform of the slidable coupling which can be used to constitute thecoupling 5 visible in FIG. 1. There is provided in the present case afemale cap 40 rigid with a shaft 41 which may be the driving shaft andthrough which a driven shaft 42 is engaged. This shaft 42 has ribs 43which are guided, when engaged into the female sleeve, by separatingwedges 44 rigid with said female sleeve. Inside this sleeve, each rib 43is arranged between a pair of cages formed in the sleeve 40 (FIG. 7)associated with balls 45 which roll along paths 46 abutted againstelastic elements 47.

It will be understood that such a coupling permits an easy relativeaxial displacement of the two shafts while ensuring adequatetransmission of the torques and an absorption of angular vibrations.Consequently, the axial and angular vibrations from the tool are nottransmitted to the universal joints.

In the showing of FIG. 9 is represented a constructional modification inwhich balls 48 are arranged between ribs 49 and rolling paths 50disposed in stepped fashion so as to facilitate penetration of the maleportion into the female portion when assembling is done.

In Fig 10 is shown a simplified constructional form of the arrangementvisible in FIG. 4. In this form, elements identical with those visiblein FIG. 4 are designated by the same reference numerals and will not bedescribed again.

In the present construction there is provided between the unions l8 and32 a one-piece cranked sleeve 51 in which is housed the head 52 of adual universal joint protected against the influence of the ambientmedium by a sheath 53 rigid with the shaft 17 and connected with acoupling 54 which may be of the type visible on FIGS. 6 to 8. Such anarrangement permits the overall lengths of the entire device to berendered smaller.

In order to modify the deflection angle, the sleeve 51 is changed byreplacing it by another one wherefor it is only sufficient to unscrewthe screw-threaded portion between the union 52 and the cranked sleeve51, then to separate the two parts of the coupling 54 and to substitutefor said sleeve another sleeve having a different deflection angle.Fitting a straight sleeve permits, should this appear to be desirable,the drilling operation to be continued without a deviating device andmay thus lead to a saving by sparing a change of turbine between twodeviation jobs.

Minor constructional details may be varied without departing from thescope of the subjoined claims.

What we claim is:

1. An equipment for directional ground drilling particularly fordrilling oil wells comprising an underground rotating motor, a drillingtool, an inflection point between said motor and tool, a first straightshaft extending between said inflection point and motor, a secondstraight shaft extending between said inflection point and tool, radialbearings for said shafts, a first axial thrust bearing for receiving theaxial thrust stress of the motor and combined with said first shaft, asecond axial thrust bearing for receiving the tool reaction and combinedwith said second shaft, and a homokinetic driving device at saidinflection point.

2. An equipment for directional ground drilling according to claim 1wherein the homokinetic driving device comprises a dual universal joint.

3. An equipment for directional ground drilling according to claim 1wherein the inflection point comprises a one-piece cranked sleeve andthe homokinetic driving device comprises a dual universal joint housedin said sleeve.

4. An equipment for directional ground drilling comprising anunderground drilling motor made up of separate first and secondsections, a drilling tool, an inflection point between both sections ofsaid motor, a first straight shaft extending between the inflectionpoint and said first section of the motor, a second straight shaftextending between said inflection point and tool through said secondsection, radial bearings for the shafts, a first axial thrust bearingfor receiving the axial thrust stress of said first motor section andcombined with said first shaft, a second axial thrust bearing forreceiving the resultant force from the axial thrust stress of saidsecond motor section and the tool reaction and combined with said secondshaft, and a homokinetic driving device at said inflection point.

5. An equipment for directional ground drilling according to claim 4,wherein the homokinetic driving device comprises a dual universal joint.

6. An equipment for directed ground drilling according to claim 4,wherein the inflection point comprises a one-piece cranked sleeve andthe homokinetic driving device comprises a dual universal joint housedin said sleeve.

7. An equipment for directional ground drilling comprising anunderground rotating motor, a drilling tool, a homokinetic drivingdevice providing an inflection point between said motor and tool, afirst straight shaft extending between said driving device and motor, asecond straight shaft extending between said driving device and tool,radial bearings for said shafts, a first axial thrust bearing forreceiving the axial thrust stress of the motor and combined with saidfirst shaft, a second axial thrust bearing for receiving the toolreaction and combined with said second shaft, and an axially slidableangular coupling interposed in one of said shafts.

8, An equipment for directional ground drilling according to claim 7wherein elastic elements are associated with said coupling for absorbingvibrations and angular impacts.

9. An equipment for directional ground drilling according to claim 7wherein said axially slidable coupling comprises a female joint, a shaftreceived in said joint, ribs and flutes respectively provided on saidfemale joint and shaft for behaving as guides, and rolling memberreceived in said guides.

10. An equipment for directional ground drilling comprising anunderground rotating motor, a drilling tool, an inflection point betweensaid motor and tool, a first straight shaft extending between saidinflection point and motor, a second straight shaft extending betweensaid inflection point and tool, radial bearings for said shafts, a firstaxial thrust bearing for receiving the axial thrust stress of the motorand combined with said first shaft, a second axial thrust bearing forreceiving the tool reaction and combined with said second shaft, ahomokinetic driving device as said inflection point, and means foradjusting the angle provided by the inflection point.

11. An equipment for directional ground drilling according to claim 10,wherein said adjusting means comprise a first sleeve, a second sleevescrewed upon the first sleeve and having an axis inclined with respectto the first sleeve axis, a revoluble ring between said first and secondsleeves, and means for angularly keying said ring in a plurality ofpositions with respect to said first and second sleeves.

1. An equipment for directional ground drilling particularly fordrilling oil wells comprising an underground rotating motor, a drillingtool, an inflection point between said motor and tool, a first straightshaft extending between said inflection point and motor, a secondstraight shaft extending between said inflection point and tool, radialbearings for said shafts, a first axial thrust bearing for receiving theaxial thrust stress of the motor and combined with said first shaft, asecond axial thrust bearing for receiving the tool reaction and combinedwith said second shaft, and a homokinetic driving device at saidinflection point.
 2. An equipment for directional ground drillingaccording to claim 1 wherein the homokinetic driving device comprises adual universal joint.
 3. An equipment for directional ground drillingaccording to claim 1 wherein the inflection point comprises a one-piececranked sleeve and the homokinetic driving device comprises a dualuniversal joint housed in said sleeve.
 4. An equipment for directionalground drilling comprising an underground drilling motor made up ofseparate first and second sections, a drilling tool, an inflection pointbetween both sections of said motor, a first straight shaft extendingbetween the inflection point and said first section of the motor, asecond straight shaft extending between said inflection point and toolthrough said second section, radial bearings for the shafts, a firstaxial thrust bearing for receiving the axial thrust stress of said firstmotor section and combined with said first shaft, a second axial thrustbearing for receiving the resultant force from the axial thrust stressof said second motor section and the tool reaction and combined withsaid second shaft, and a homokinetic driving device at said inflectionpoint.
 5. An equipment for directional ground drilling according toclaim 4, wherein the homokinetic driving device comprises a dualuniversal joint.
 6. An equipment for directed ground drilling accordingto claim 4, wherein the inflection point comprises a one-piece crankedsleeve and the homokinetic driving device comprises a dual universaljoint housed in said sleeve.
 7. An equipment for directional grounddrilling comprising an underground rotating motor, a drilling tool, ahomokinetic driving device providing an inflection point between saidmotor and tool, a first straight shaft extending between said drivingdevice and motor, a second straight shaft extending between said drivingdevice and tool, radial bearings for said shafts, a first axial thrustbearing for receiving the axial thrust stress of the motor and combinedwith said first shaft, a second axial thrust bearing for receiving thetool reaction and combined with said second shaft, and an axiallyslidable angular coupling interposed in one of said shafts. 8, Anequipment for directional ground drilling according to claim 7 whereinelastic elements are associated with said coupling for absorbingvibrations and angular impacts.
 9. An equipment for directional grounddrilling according to claim 7 wherein said axially slidable couplingcomprises a female joint, a shaft received in said joint, ribs andflutes respectively provided on said female joint and shaft for behavingas guides, and rolling member received in said guides.
 10. An equipmentfor directional ground drilling comprising an underground rotatingmotor, a drilling tool, an inflection point between said motor and tool,a first straight shaft exTending between said inflection point andmotor, a second straight shaft extending between said inflection pointand tool, radial bearings for said shafts, a first axial thrust bearingfor receiving the axial thrust stress of the motor and combined withsaid first shaft, a second axial thrust bearing for receiving the toolreaction and combined with said second shaft, a homokinetic drivingdevice as said inflection point, and means for adjusting the angleprovided by the inflection point.
 11. An equipment for directionalground drilling according to claim 10, wherein said adjusting meanscomprise a first sleeve, a second sleeve screwed upon the first sleeveand having an axis inclined with respect to the first sleeve axis, arevoluble ring between said first and second sleeves, and means forangularly keying said ring in a plurality of positions with respect tosaid first and second sleeves.